Time filter

Source Type

Xu S.-Q.,China Power Engineering Consulting Group Corporation
Journal of Railway Engineering Society | Year: 2014

Research purposes: As a result of the limitation of engineering site condition, jacking construction method is the only method to be adopted for the large-span curve concrete bridge. For the concrete box girder, which is 250 000 kN in weigh, 213 m in top range and 920 m in radius, the center line in the process of pushing trajectory and the size of the temporary pier horizontal force are the key issues for the design and construction of box girder pusher which is in big tonnage and long range curve. This paper is intended to find ways to solve these problems. Research conclusions: Based on the research on the pushing force and motion of main girder in process of Shangdi Bridge single cable plane curve of prestressed concrete cable-stayed bridge jacking on Beijing-Xinjiang Highway, it can reach the following conclusions: (1) Put forward a new method of the construction of complex curve of concrete box girder, by which it can simplify the design of the ramp and spacing device, and control pusher track of the complex curve girder. (2) Because two-point limit structure is statically determinate system in the horizontal plane, it can be calculated accurately the level of the working condition of the limit force pushing process. And the temporary pier horizontal reaction greatly reduced to the only 1.2‰ of pushing weight, which provides the technical support for the construction security of weight of the complex curve girder pusher. (3) Two-point limit method is suitable for the complex curve prestressed concrete box girder bridge construction of roads, railways and municipal engineering which using the jacking method.

Jia N.,China Power Engineering Consulting Group Corporation
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

Based on the concept of mobilized angle of internal friction, the coefficient of at-rest earth pressure from limited coarse backfill K 0 is obtained after the analysis of the Mohr's cycle. A comparison is made with Jaky's formula for half infinite soil mass K 0J and active earth pressure from limited backfill K a. It is found that K 0 is close to or smaller than K 0J, when the internal friction angle between the rock face and backfill δ r is equal to that of backfill ψ. K 0 is not only influenced by ψ and inclination of the rock face, but also by δ r; K 0 may be larger or smaller than K 0J, when δ r is smaller than ψ; K 0 and K a decrease with the increase of the inclination of the rock slop; and K 0 is larger than K a. To make the rock face rough and to adopt bench excavation are both effective methods to reduce the at-rest earth pressure from the limited backfill. A design graph is given at the end of the paper.

Zhao B.,Tsinghua University | Song Q.,Tsinghua University | Liu W.,Tsinghua University | Sun W.,China Power Engineering Consulting Group Corporation
IEEE Transactions on Industrial Electronics | Year: 2013

By establishing the mathematical model of the current stress of the isolated bidirectional dc-dc converter (IBDC), this paper comparatively analyzes the performances of IBDC under traditional single-phase-shift control and dual-phase-shift (DPS) control. On this basis, this paper proposes a current-stress-optimized switching strategy for IBDC with DPS control, and the corresponding control scheme is designed and implemented. The current-stress-optimized switching strategy can minimize the current stress, improve the system efficiency, and increase system power capability, and these performances are particularly effective for operation conditions with high voltage conversion ratio and light load. At last, experimental results verify the excellent performance of the current-stress-optimized switching strategy and correctness of the theoretical analysis. © 1982-2012 IEEE.

Li N.,Chongqing University | Li J.,Chongqing University | Fan R.,China Power Engineering Consulting Group Corporation | Jia H.,Chongqing University
Renewable Energy | Year: 2015

Window operation is not only an important method for improving the indoor thermal environment and air quality, but also a significant way to reduce energy consumption of air-conditioned rooms during off-running periods in transition seasons. The occupants' window-operation behavior is influenced by both objective factors, such as thermal comfort and indoor air quality; and objective sensation, such as psychology and physiology, introducing considerable randomness and uncertainty. A two-month field observation of occupant window-opening behaviors for natural ventilation in an office building during the transition seasons was carried out in Chongqing, China. Multi-factor analysis of variance was conducted in data analysis using SPSS statistical software. The results showed that outdoor air temperature significantly affected window opening among other factors such as outdoor relative humidity, indoor air temperature, indoor relative humidity, and indoor CO2 concentration, which have much less effect. The main trigger point for opening windows in the transition seasons is from occupants' desire to improve the indoor thermal and air quality environment. A probability model of occupants' window operation was proposed based on logistic regression analysis. Meanwhile, the Monte Carlo simulation results indicate that during transition seasons (when outdoor temperature varied from 15 to 30°C), the probability of window opening in office buildings follows a normal distribution and increases linearly along with the outdoor temperature growth. © 2014 Elsevier Ltd.

Guo Y.-T.,CAS Wuhan Institute of Rock and Soil Mechanics | Yang C.-H.,CAS Wuhan Institute of Rock and Soil Mechanics | Fu J.-J.,China Power Engineering Consulting Group Corporation
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

With the project of Jintan underground gas storage, taking the cavity actual bearing conditions as the object of study, carrying out unloading confining pressure test of salt rock under different conditions, the complete stress-strain curves, deformation characteristics are obtained. The test results show that axial and radial strains increase slowly in the initial stage of unloading confining pressure; and the relation between strain and confining pressure is linear. Along with the confining pressure continuous decrease, axial and radial strain values increase sharply. Comparing the loading and unloading curves, under the conditions of the same maximum principal stress, when the unloading confining pressure is the same as triaxial compression pressure value, the axial and radial strains variations are larger than that of loading conditions. Under the same initial stress conditions, the changing magnitude of stress required for rock failure is less than that of triaxial compressive process. It is shown that the plastic deformation of salt rock is different from hard rock of brittle failure under unloading confining pressure. The conclusion can be useful in underground gas storage engineering stability analysis and gas injection/extraction process.

Li L.P.,China Power Engineering Consulting Group Corporation
Applied Mechanics and Materials | Year: 2014

This paper addresses the challenges in performance monitoring and degradation diagnosing of complex industrial process. A Bayesian network-based model was developed using real operation data of the system, and readings from multiple sensor sources were regarded as evidences to identify the root cause of process variations causing system degradation. An inferring process was executed with the belief network to output possible root causes of the process variation. Then, a probabilistic confidence level of controllable variables was recommended for optimizing operation. A full-scope simulator for the power plant unit is employed as an indispensable test bed for the probabilistic network model. To achieve a decision support simulation, a simulated operation database is generated through varying boundary parameters. The model was re-parameterized with the data from the simulated operation database. The simulation test results show that the model can properly represent the domain knowledge, and the decision advices are effective for such an elaborate work. The probabilistic model can tackle the problems which are indiscernible in conventional thermodynamic model-based analysis. © (2014) Trans Tech Publications, Switzerland.

Zhao B.,Tsinghua University | Yu Q.,Tsinghua University | Sun W.,China Power Engineering Consulting Group Corporation
IEEE Transactions on Power Electronics | Year: 2012

This paper points out a phenomenon of power backflow in traditional phase-shift (TPS) control of isolated bidirectional full-bridge DC-DC converter (IBDC), and analyzes the effects which backflow power act on power circulating flow and current stress. On this basis, the paper proposes a novel extended-phase-shift (EPS) control of IBDC for power distribution in microgrid. Compared with TPS control, EPS control not only expands regulating range of transmission power and enhances regulating flexibility, but also reduces current stress and improves the system efficiency. The operation principle of EPS control and the operation modes of IBDC are analyzed in the paper. By establishing mathematical models of transmission power, backflow power, and current stress, the paper comparatively analyzes control performances of TPS and EPS control. At last, experimental results verify the excellent performance of EPS control and correctness of the theoretical analysis. © 2012 IEEE.

Zhao B.,Tsinghua University | Yu Q.,Tsinghua University | Sun W.,China Power Engineering Consulting Group Corporation
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

In order to reduce the power circulating flow in bi-directional full-bridge DC-DC converters, this paper analyzed the backflow power characteristic of converter. On this basis, the paper presented a dual-phase-shifting control method. The operation principle of the dual-phase-shifting control and the operation stages of the converter were analyzed in the paper. By establishing mathematical models of transmission power and backflow power, the paper comparatively analyzed control performances of the traditional phase-shifting control and the dual-phase-shifting control. At last, experimental results verify the excellent performance of the dual-phase-shifting control. © 2012 Chinese Society for Electrical Engineering.

Huang J.,Zhejiang University | Li B.,Zhejiang University | Jiang H.,China Power Engineering Consulting Group Corporation | Kang M.,Zhejiang University of Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, a multiphase bearingless motor (MBLM) with a single set of half-coiled winding is proposed, with advantages such as simpler construction and capability of fault-tolerant operation, comparing with the traditional BLM with dual groups of three-phase windings. The magnetomotive force distribution of the half-coiled winding is analyzed. Then, the winding configuration of a five-phase permanent-magnet bearingless motor is introduced, and the inductance of the MBLM is deduced by the modified winding function approach and verified by finite-element analysis. Furthermore, the control system is proposed based on the derived voltage model, torque model, and suspension force model, considering rotor eccentricity. Finally, static and dynamic experiments are provided on a prototype motor to verify the validity of the analysis. © 1982-2012 IEEE.

China Power Engineering Consulting Group Corporation | Date: 2012-11-07

A feedwater and draining system for medium-pressure heaters used in a power plant comprises a feedwater piping (100) and a boiler feedwater pump unit (200) provided on the feedwater piping (100).The boiler feedwater pump unit (200) includes a low-pressure boiler feedwater pump (203) and a high-pressure boiler feedwater pump (204) provided along the upstream and the downstream of the feedwater piping (100). A medium-pressure feedwater heater unit (300) comprising one or more feedwater heaters is provided between the low-pressure boiler feedwater pump (203) and the high-pressure boiler feedwater pump (204).A generator set and a power plant equipment comprising the feedwater and draining system for the medium-pressure heater are provided. The feedwater and draining system for the medium-pressure heater is low in cost, high in efficiency of thermodynamic system and more environment-friendly.

Loading China Power Engineering Consulting Group Corporation collaborators
Loading China Power Engineering Consulting Group Corporation collaborators